Frame construction for turbojet engines



Nov. 27, 195] c. N. LAWTER FRAME CONSTRUCTION FOR TURBOJET ENGINES 2SHEETS-SHEET 1 Filed Feb. 4, 1948 N R m mm mm, rn Aw m w ww bum w oh NWQW m$ N9 m mum m QN Aw MIN kw NW) RN Q%/ I IN VENTOR. Cari 1.6 JYZcal/fez Nov. 27, 1951 c. N. LAWTER FRAME CONSTRUCTION FOR TURBOJETENGINES 2 SHEETS SHEET 2 Filed Feb. 4, 1948 i IN VENTOR.Czzrizs/l/Lazdir:

Patented Nov. 27, 1951 FRAME CONSTRUCTION FOR TURBOJET ENGINES Curtis N.Lawter, Trenton, N. J., assignor to Packard Motor Car Company, Detroit,Mich., a corporation of Michigan Application February 4, 1948, SerialNo. 6,318

(01. Gil-39.31)

1 Claim. 1

The invention relates generally to a turbo-jet engine and moreparticularly to a frame construction therefor.

The general object of the invention is to provide a novel framestructure for a turbo-jet engine, the frame structure serving to carrythe drive shaft connecting the turbine with the air compressor and toprovide a rigid structure to which various parts of the casing structuremay be secured.

Another object is to provide a novel frame structure of the foregoingcharacter, which provides the necessary rigidity for support of thedrive shaft and casing structure, and which is of relatively lightweight and may be easily manufactured.

Still another object is to provide a frame structure of the foregoingcharacter, which minimizes the gyroscopic moment of the turbine'on theinternal structure of the engine.

Other objects and advantages will.become apparent from the followingdescription taken in connection with the accompanying drawings, inwhich:

Figure 1 is a horizontal longitudinal sectional view through a turbo-jetengine having a frame construction embodying the features of theinvention.

' Fig. 2 is a front elevational view of the frame structure shown inlongitudinal section in Fig. 1, as viewed substantially from the line2--2 of Fig. 1.

Fig. 3 is a transverse sectional view taken substantially on the line3-3 of Fig. 1.

A turbo-jet engine of the character herein contemplated is illustratedin Fig. l and is shown as comprising an inlet cover I having a centralfront opening or eye I! through which air is drawn in by a rotarycompressor I2, the compressor I2 being located within the inlet coverID. The compressor I2 is mounted on a main shaft I3 axially positionedwithin the engine and having its front end journaled in a bearing I4supported by struts I5 extending radially withinthe inlet opening II.The air drawn inwardly by the compressor I2 is discharged radially withan axial component into a diffuser passage provided by a diffusersection I6. From the diffuser It the air is discharged into an annularcombustion chamber section I! where the fuel is supplied by means ofburners 20. The power stream generated in the combustion chamber sectionI! is discharged rearwardly therefrom to act on turbine blades 2|carried on a turbine rotor 22. The main shaft I3 extends rearwardly fromthe air compressor I2 and, at its rear end, supports the turbine rotor22. The turbine rotor 22 and the air compressor I2 are thus directlyconnected. The turbine, of course, absorbs a portion of the energy inthe power stream emerging from the combustion chamber section I! toprovide power for driving the air compressor !2. The power stream, afterpassing through the turbine blades 2!, flows into a tail cone, indicatedgenerally at 23, from which the power stream emerges through an opening24 at the rear end thereof to form the jet.

An engine of this character is, of course, adapted to be mounted in thebody of an aircraft, and to provide for such mounting, the diffusersection I6, which is in the form of a rigid casting, may be provided onits exterior with a pair of diametrically opposite mounting lugs 25. Thediffuser section I6 comprises an outer wall 26 and an inner wall 2?connected by flow-controlling vanes 30 lying in the passage provided bythe space between the inner and outer walls 26 and 21. The inlet coverI0 is secured at its rear end to the diffuser section It so as toprovide a rigid connection therebetween. The combustion chamber sectionI! preferably comprises a sheet metal casing structure including aninner wall 3| and an outer wall 32. The tail cone 23 is similarly formedfrom sheet metal and constitutes a continuation of the combustionchamber section I1.

To support the main shaft I3 so that the air compressor I2 is properlypositioned within the inlet cover I0 and the turbine rotor 22 is held inproper relation to the annular combustion chamber, and to provide rigidsupport for the sheet metal casing structure forming the combustionchamber I1, a main frame, indicated generally at 33, is provided, whichforms a backbone for the engine as a whole. Generally described, themain frame 33 is secured to the rigid diffuser section It and isprovided with suitable bearings for supporting the main shaft I3. Themain frame is of elongated form and projects rearwardly so that one ofthe bearings is located adjacent the turbine rotor 22 to give adequatesupport therefor. The combustion chamber section I! is supported at itsfront end by the diffuser section I6 adjacent the point of attachment ofthe latter to the main frame 33, and at its rear end the combustionchamber section I! is provided with additional support extending fromthe rear end of the main frame adjacent the turbine rotor 22. The mainframe is in the form of a rigid casting which may be gener- 3 allydescribed as comprising a pair of truncated cones positioned base tobase with the diffuser section l6 and the front end of the combustionchamber section I1 located at the point where the bases of the two conesmeet intermediate the ends of the main frame 33. With the main frame 33constructed in the manner herein disclosed, the effect of the gyroscopicforce of the turbine rotor 22 on the internal structure of the engine isminimized by the fact that it acts through a relatively short lever arm.

Referring to the details of structure of the main frame 33, in Fig. 1,where a longitudinal section of the frame is shown, it is apparent thatthe frame comprises a pair of truncated conical portions 34 and 35, thecones being positioned base to base with the small ends of the conesconstituting the ends of the frame member. In the present instance, therear cone portion 35 is shown as having a greater axial length than thefront cone portion 34. The frame member is hollow and its ends providesupport for the main shaft |3. Thus, as is clearly illustrated in Fig.l, I provide a bearing 36 in the front end of the frame member 33, whichpreferably is in the form of a thrust bearing to take up the thrustimposed on the main shaft |3 by the turbine rotor 22. Stifiening ribs 38may be formed on the frame member adjacent the bearing 36 to provideadequate support therefor. The rear end of the main frame member 33carries a bearing 31 which is of the type providing for radial supportof the shaft l3.

Intermediate the ends of the main frame [3, I provide a peripheralflange 46 thereon for securing the rear end of the difiuser section Hithereto. In the present instance, the inner wall 21 of the diffusersection I6 is shown as being secured to the flange 43 by means of aplurality of circumferentially spaced bolts 4|. The inner wall 3| of thecombustion chamber section is mounted on the inner wall 21 of thediffuser section 6, while the outer wall 32 of the combustion chambersection is secured to the outer wall 26 of the diffuser section I3.Thus, the main frame member is bulged outwardly intermediate its ends toconnect with the diffuser section I6, and since the latter carries themounting lugs 25 by which the engine as a whole is supported, the mainframe thus provides a rigid support for the main shaft l3 and the sheetmetal casing structure comprising the combustion chamber section I! andthe tail cone 23. The front cone portion 34 of the-frame member may beprovided with a channel-shaped bulge, shown at 42 in Figs. 1 and 2, toform a sump for oil supplied to the bearings 35 and 31 and collectingwithin the frame member 33.

At the rear end of the main frame member 33 adjacent the bearing 31, asupport is provided for the rear end of the combustion chamber sectionH. For this purpose, the main frame is provided with a peripheral flange43 at its rear end. Secured to the flange 43, as by bolts 44, is adisclike member constituting a dished diaphragm 45 extending outwardlyand toward the turbine rotor 22. Secured to the periphery of thediaphragm 45 is a ring member 46 carrying nozzle 4 W blades 41 fordirecting the power stream from the combustion chamber section l1 at theproper angle to the turbine blades 2|. The ring member 46 is secured tothe diaphragm 45 in a manner which holds them in truly concentricrelationship but, because of the fact that the ring member 46 issubjected to the high heat of the power stream, relative expansionbetween the ring member and the diaphragm member takes place. To thisend, the diaphragm, adjacent its periphery, i provided with pairs oflugs 50 having radially aligned apertures to receive radially positionedpins 5| extending outwardly through the ring member 46. The pins 5| thushold the ring member and diaphragm concentric to one another, but,should the ring member expand, it is free to slide outwardly on the pins5|. The rear end of the inner wall 3| of the combustion chamber sectionI! is mounted on the ring member 43 and consequently is supported fromthe rear end of the frame member 33.

From the foregoing description, it is apparent that the main framemember 33 supports the shaft I3 and, since the main frame member 33 isconnected to the diffuser section It carrying the mounting lugs 25, arigid support from the external mounting of the engine is provided forthe parts. The sheet metal casing structure forming the combustionchamber section I! is supported at its front end by the diffuser sectionand at its rear end by the diaphragm 45, so that the combustion chambersection II is properly held in concentric relation to the turbine rotor22.

I claim: 7

In a turbo-jet engine, a one-piece elongated hollow frame membercircular in cross section and bulged outwardly intermediate its ends, arigid shaft extending through said frame member and journaled in theends thereof, a turbine rotor mounted on one end of said shaft and anair compressor on the other end, a rigid annular casting providing anair diffuser section having its rear end extending about and directlysecured to the bulged portion of said frame member and flaring forwardlytherefrom, an annular sheet metal combustion chamber section secured tosaid casting in concentric relation therewith and ex tending rearwardlytherefrom, a rigid supporting diaphragm secured to the rear end of saidframe member and supporting the combustion chamber section rearwardly ofsaid casting, and supporting members rigidly formed on and extendingradially from said rigid casting adjacent its rear end for supportingthe engine.

CURTIS N. LAWTER.

REFERENCES CITED The following references are of record in the filo ofthis patent:

UNITED STATES PATENTS

